Demands for more and better information on fiber properties have steadily risen from the beginning of the industrial revolution until today. Production rates of textile processing machinery have dramatically increased, especially in the past 25 years. Tolerances for variations in fiber properties have, correspondingly, dramatically decreased as speed and quality demands have risen. To achieve better control over quality, while increasing production speed, represents a major challenge for modern manufacturing, a challenge which can only be met with improved information, in vastly increased quantities, about the raw materials of textile manufacturing, fibers, both natural (cotton, wool, etc) and man-made (polyester, nylon, etc.).
These observations about modern textile manufacturing apply as well to modern aerosol manufacturing. Production rate increases and decreases in tolerance for variations in particular sizes demand more and better information as well.
Accordingly, this invention is in the field of electro-optical measurement of the physical properties of fibers and aerosols; the invention is part of and enables a system whereby heretofore impossibly accurate, precise, reliable, fast, and cost-effective information can be generated on a wide variety of physical properties of fibers and aerosols.
A brief historical overview of prior art in the fiber testing will clarify the relation of this system to it and especially the major improvements this invention makes in fiber testing. A similar overview could be set forth for aerosol testing.
In the mid-1800s, when only natural fibers were available, the revolutionary technology of that period, water-or steam-powered machinery, already demanded more and better information.
Standards for cotton, for example, were established and cotton classers or graders painstakingly learned and applied their trade to assure that "smooth and even-running" lots were delivered to the mills. The Liverpool Staple Standards became the most widely used until, in the early 1900's, the United States Department of Agriculture began to dominate, world-wide, the definition, preparation, and supply of standard cotton materials, which they do even today.
In the 1960's, in response to demands for more and better information, the USDA began to consolidate developments in instrumental fiber testing. One approach, conducted by Stanford Research Institute for the USDA, was to measure cotton fiber length and diameter electro-optically. The fibers were individually presented to the measurement zone by a combination of aerodynamic and electro-static forces. Severe difficulties with the generation and the presentation of single fibers and low data rate, less than 1 fiber/second, led to abandonment of this approach.
The successful approach to so-called "High Volume Instrument" lines simply used faster-operating versions of already-existing laboratory instruments. These instruments indirectly measure fiber length, strength, diameter, and color. Prototypes were completed by the mid-1970's but the technology was rejected by certain parties in the trade and lay dormant until 1980 when pressure from dissatisfactions with manual classing caused farmers in Lamesa, Tex. to insist on HVI. Today about 50% of US cotton is classed by HVI; by 1992, almost 100% will be. It is expected that most of the world cotton crop will be instrument-classed by around the year 2000, not necessarily with current-generation, but with improved fiber testing instrument technology, some of which is the subject matter of this invention.
The basic technology for current generation HVI measurements is 25-75 years old except for the computers used to automate them and to process the data. It is becoming clear, unfortunately, that these older test methods do not and cannot provide the advanced fiber information, the "more and better information" required by modern textile processing.
Two or more operators are required and testing time averages about 1/2 minute. Never-the-less, current generation HVI has enabled a major marketing breakthrough.
It was recognized in the early 1980's that Research and Development upon the next generation HVI must begin as soon as possible and even before HVI was widely accepted or even widely known. The concept advanced by the first-named inventor of this invention, that of measuring, directly and at high speed, physical properties of single entities in the fiber sample, were accepted by forward-looking leaders in fiber testing and marketing as a candidate technology. These more basic measurements provide the more and better information needed by modern textile manufacturing. They are more basic because single entities (single fibers, single neps, single trash particles, single microdust particles, etc.) are directly measured rather than indirectly by measuring bulk or bundle properties.
Equally importantly, they are more basic because statistical distributions are easily formed with the aid of modern electronics technology.
These concepts led to various prototype systems that are called the Advanced Fiber Information Systems (AFIS) and consist of: (1) aeromechanical separator or fiber individualizer, (2) high speed, single entity sensors, and (3) high information rate, personal-type computer. Only the latter is well-known in the art of modern electronics.
The aeromechanical separator is described in U.S. Pat. Nos. 4,512,060; 4,631,781; and 4,686,744.
Sensor means for single fiber strength measurement are described in co-pending U.S. application "Fiber Testing Apparatus and Method", Ser. No. 07/460,292.
Prior art electro-optical sensors are described in U.S. Pat. Nos. 4,249,244; 4,396,286; 4,473,296; and 4,885,473.
For AFIS fiber testing applications, various open literature contributions have been made such as:
1. "Advanced Fiber Information Systems: A New Technology for Evaluating Cotton":, by F. M. Shofner, G. F. Williams, C. K. Bragg, and P. E. Sasser (December 1988 presented at the Textile Institute Conference Fiber Science Group, U.K.).
2. "Advanced Technology for Measuring Cotton Fiber Length, Diameter, and Trash Content" by C. K. Bragg (March 1988).
3. "An Objective Method for Counting and Sizing Neps" by P. F. Sasser (March 1988).
For simplicity, we refer to our prior art, prototypical, electro-optical (E-O) fiber testing technology and embodiments as AFIS 0. AFIS 0 included a fiber individualizer, a fluid stream, a nozzle for accelerating the fluid stream, a converging beam of light and a forward light scattering detector. It did not include, among other things, a speed sensor, an extinction mode sensor or a substantially collimated beam of light. We refer to the improved E-O technology for fiber and aerosol testing of this invention as AFIS 1. It will be seen that AFIS 1 provides new data products, some previously impossible, and new E-O means, over AFIS 0.
Practical experience with AFIS 0 demonstrated that the concepts of high speed measurement single entities, followed by calculation of statistical distributions, are urgently needed. Prior art measurements are increasingly seen as inadequate and even misleading for modern textile manufacturing. Indeed, recently-accelerating demands for more and better information provided the motivation to research and to develop these AFIS 1 improvements over AFIS 0, which itself already provided improvements over current-generation HVI.
Accordingly, it is the broadest objective of this invention to provide improved fiber and aerosol measurements over prior art, including AFIS 0. The improvements are in all major categories of accuracy, precision, reliability, speed, and cost-effectiveness. Most importantly, the E-O improvements herein disclosed provide more basic information than previously possible.
Another objective is to provide a fiber testing system and method which, in combination with other features and measurements, such as single fiber strength or color, enables a single operator HVI System with test zone environmental control and which can ultimately operate at test times of 1/4 minute.
A further objective is to provide aerosol testing apparatus and methods which enable laboratory quality control instruments or ultimately, on-line, closed-loop control systems for aerosol manufacturing.
Another objective is to provide monovariate statistical distribution information on at least these entities in fiber samples: length, diameter, fineness, maturity, color, shape, surface roughness, for the fibers themselves; neps; trash particles; dust and microdust particles. Neps, trash, dust and microdust are regarded as undesirable elements in the fibrous mass.
Yet another objective is provision of multivariate statistical distribution information as, for example, bivariate distributions in fiber length and diameter or trivariate distributions in particle diameter, shape, and surface roughness.
Whereas the broader user-related objectives provide for more and better information on physical characteristics of fibers or aerosols, a more specific objective of this electro-optical invention is to enable measurement of fiber or aerosol speed and acceleration in the scattering zone and to use this data to provide more absolute readings of length and improved readings of other physical characteristics such as diameter, fineness, maturity, color, shape, and surface roughness and the like.
A still further objective of the invention is to provide for simultaneous measurement of 2 or more scattering angles.
A similar further objective is to provide for measurements using simultaneously-emitted electromagnetic radiation components having 2 or more principal or mean wavelengths and 2 or more states of polarization.
The ultimate objective is to optimally combine these new electro-optical sensor means with suitable fiber or aerosol individualizer means and modern electronics means into systems which provide more and better fiber or aerosol information, as demanded by modern manufacturing.